Ecology of Olive Ridley Sea Turtles at Arribadas at Playa La Flor, Nicaragua

Paresis as a limiting factor in the reproductive efficiency of a nesting colony of Lepidochelys olivacea (Eschscholtz, 1829) in La Escobilla beach, Oaxaca, Mexico

Rear flippers are crucial in the nesting process of Olive Ridley Turtles Lepidochelys olivacea, so any impact on them could constitute a limiting factor in reproductive efficiency. Muscle weakness of the rear legs has been observed in some nesting females on La Escobilla beach in Oaxaca state, Mexico; however, this disorder has not been sufficiently researched. The aim of this study was to identify and describe this problem in a nesting colony of L. olivacea in La Escobilla. We obtained the biochemical profiles of eight females with clinical signs of muscle weakness of the rear legs, that could not build the incubation chamber for their nest. In order to compare their blood characteristics, we selected eight seemingly healthy turtles that successfully built their nests, laid eggs through oviposition and covered the nest. We found no significant differences in most of the blood parameters, except for Creatinine-Kinase (CK). Female turtles with muscle weakness presented significantly higher concentrations of CK (t = 2.1448, d.f. = 2, P <0.0001) when compared to the healthy turtles. CK is an appropriate enzyme for identifying the integrity of the muscle cell and is a muscle damage indicator. Our hypothesis is that the paresis observed in the rear legs of the female turtles in La Escobilla could be a chronic debilitation caused by a gradual exposure to biotoxins such as saxitoxins.

Threats and Vulnerabilities for the Globally Distributed Olive Ridley (Lepidochelys olivacea) Sea Turtle: A Historical and Current Status Evaluation

The olive ridley (Lepidochelys olivacea) is the most abundant of all seven sea turtles, found across the tropical regions of the Atlantic, Pacific, and Indian Oceans in over 80 different countries all around the globe. Despite being the most common and widely distributed sea turtle, olive ridley populations have been declining substantially for decades. Worldwide, olive ridleys have experienced a 30–50% decline, putting their populations at risk and being considered an Endangered Species by the IUCN. Natural habitat degradation, pollution, bycatch, climate change, predation by humans and animals, infectious diseases and illegal trade are the most notorious threats to explain olive ridley populations rapidly decline. The present review assesses the numerous dangers that the olive ridley turtle has historically faced and currently faces. To preserve olive ridleys, stronger conservation initiatives and strategies must continue to be undertaken. Policies and law enforcement for the protection of natural environments and reduction in the effects of climate change should be implemented worldwide to protect this turtle species.

Corozalito: a nascent arribada nesting beach in Costa Rica

Costa Rica hosts two renowned olive ridley (Lepidochelys olivacea) arribada beaches: Nancite and Ostional. In addition, the country hosts a third nascent arribada beach in Corozalito. We documented the frequency of arribada events in Corozalito (9°50'55.40″ N; 85°22' 47.67″ W) from 2008 to 2021 and the abundance of egg-laying females during 12 arribadas. Moreover, we report on tag recaptures at Corozalito that were initially deployed at other nesting beaches in Costa Rica. Finally, we estimated incubation temperature, and performed quadrat and nest excavations to estimate hatching rates. We registered 29 arribadas at Corozalito since 2008, all between August and January. We estimated more than 150,000 olive ridleys nested during 12 arribadas from 2019 to 2021. Mean hatching success was 65% in quadrats and 59% for in situ marked nests. The mean incubation temperature was 32.3 °C. We found turtles tagged at other locations on the Pacific coast of Costa Rica nesting at Corozalito, providing evidence of philopatric plasticity. We suggest nascent arribada rookeries form rapidly via recruitment from regional turtle aggregations. Our findings show that hatching success is far higher at Corozalito than Ostional or Nancite. Continued monitoring of nesting dynamics at this site may shed light upon the mechanisms that rule how arribada beaches are born and evolve. Corozalito offers a unique opportunity to study and understand the arribada phenomenon and warrants official protection under official National Wildlife Refuge status.